,-*- xbd_chap05.html -*-| The EXTENDED DESCRIPTION section almost exactly matches the| printf() function in the ISO C standard, although it is described| in terms of the file format notation in the Base Definitions volume| of IEEE Std 1003.1-2001, Chapter 5, File Format Notation.`-*-In other words, it does *not* match it at all. How it can withoutthe length modifiers?

As for me, "shalls" and "shoulds", "Implementations are encouraged" arestandard terms of The Standards.